Securing communication within a network endpoint

ABSTRACT

Systems and methods for securing communication within a network endpoint, for example, a meter. The meter may include a communication module and a metrology module where the modules are connected via a communication path that is external to both modules. The modules exchange a pairing key to establish a paired channel of communication. When the communication module receives a communication through a network for establishing a secure channel to the endpoint, the communications module sends some or all of the security data to the metrology module to establish a secure communication from a head-end system through the communication module to the metrology module.

CROSS-REFERENCE TO RELATED APPLICATION

This is a continuation application of U.S. patent application Ser. No. 14/045,103 filed Oct. 3, 2013, now allowed, the entire contents of which is incorporated herein by reference.

TECHNICAL FIELD

This disclosure relates generally to data communications and more particularly relates to securing communications within a network endpoint.

BACKGROUND

A metering network may be used to communicate between a resource provider and devices that monitor and control resources, such as electricity, in a home or other location. An example is an electric utility company and the meters located at their customer's houses or businesses. Utility companies and other resource providers may use a metering network to monitor, control, and measure the consumption of resources by consumers. Secure communications between and within devices in a metering network is crucial to allow accurate and uninterrupted operation of the metering network.

The flow of communication in a metering network may be from a head-end system through collectors, routers, and other meters to a meter or endpoint at a specified location. Having many network entry points can increase exposure to potential attackers. If left unsecured, entry points are vulnerable to tampering that might allow an attacker to penetrate the network, gain access to control software, and alter load conditions to destabilize the distribution grid. Previous solutions for providing security in a metering network cover the network from the head-end system to the endpoint or meter at a specified location. Meters may be vulnerable to tampering since they are geographically dispersed and may not provide secure communication within the endpoint or meter. Accordingly, systems and methods are desirable for providing secure communication within an endpoint that does not impact the flow of secure communication in the metering network.

SUMMARY

Systems and methods are disclosed for providing secure communication within an endpoint that does not impact the flow of secure communication in a metering network. An exemplary method includes receiving a communication through a network by a communication module, the communication containing security data sent to a meter for establishing a secure channel through the network to the meter. The meter includes a communication module and a metrology module externally linked via a communication path. A paired channel is provided through the communication path through the use of a pairing key. The exchange of security data between a head-end system and the communication module and the exchange of the same or similar data between the communication module and the metrology module ensures secure communication within the meter and avoids any impact to the flow of communication in the metering network.

These illustrative aspects and features are mentioned not to limit or define the invention, but to provide examples to aid understanding of the inventive concepts disclosed in this application. Other aspects, advantages, and features of the present invention will become apparent after review of the entire application.

BRIEF DESCRIPTION OF THE FIGURES

These and other features, aspects, and advantages of the present disclosure are better understood when the following Detailed Description is read with reference to the accompanying drawings, where:

FIG. 1 is a diagram illustrating a metering network from head-end system to an endpoint;

FIG. 2 is a metering network illustrating the network from a head-end system or controller to an endpoint;

FIG. 3 is a diagram illustrating an endpoint with a communication module and a metrology module;

FIG. 4 is a diagram illustrating the exchange of keys between a head-end system and an endpoint, and between the communication module and the metrology module in the endpoint;

FIG. 5 is a flowchart illustrating how network data is processed when a secure communication is established between the head-end system and the metrology module of the endpoint; and

FIG. 6 is a flowchart illustrating how metrology data is processed when a secure communication is established between the head-end system and the metrology module of the endpoint.

DETAILED DESCRIPTION

Systems and methods are provided for securing communication within an endpoint in a network. Though an endpoint may be designed to be a final node in a network, communication within the endpoint must also be secured. This is of primary importance when modules within the endpoint are connected via a communication path that is external to the modules. An example of an endpoint is a meter. The purpose of a meter is to control, monitor and measure the consumption of a resource by a consumer. In addition, today's meters also must have the functionality to receive and respond to commands transmitted over the network. To do this, a meter may include separate modules. One module, the communication module, performs the functions needed for data communication across the network. Another module, the metrology module, performs the functions needed to control, monitor and measure the consumption of a resource. The metrology module and the communication module may be connected via a communication path that externally links these two modules. One communication module may be connected to one or more metrology modules. The communication module and each of the metrology modules may be on separate electronic boards linked through a board socket. Alternatively, the communication module and each of the metrology modules may be connected through a communication cable or other external conductor.

An endpoint or meter may be controlled by a head-end system. A head-end system enables a user to remotely program meters, schedule time-of-use periods and rates, handle remote disconnects, analyze critical peak usage, view load control indices, and perform other day-to-day functions. To accurately do this, the channel over the network that the head-end system uses to communicate with the meter must be a secure channel. The secure channel over the network is established by the exchange of security data between the head-end system and the endpoint. The security data may include various cryptographic keys used for encryption/decryption of data, validation of data, and authentication of data. This secure channel that is set-up between the head-end system and the endpoint is extended to any communication within the endpoint.

In an example of the present invention, the endpoint or meter includes a communication module connected to one or more metrology modules. The communication module is linked to each metrology module via a communication path that is external to both modules. If the communication module and a metrology module are on separate circuit boards, the communication path may be a board socket. In another embodiment of the present invention, the communication module and a metrology module may be housed in separate units and the communication path may be a cable.

Since the communication module and each of the metrology modules are externally connected via a communication path, a secure channel must be set up on the communication path to guarantee secure communication between the communication module and any of the metrology modules. During manufacturing of the meter the pairing key may be injected into the modules. If the pairing key is injected during manufacture, an acknowledgement between the communication module and each of the metrology modules may be performed to confirm that a pairing key has been established. Alternatively, during installation or initialization of the meter, a pairing key may be exchanged between the communication module and each of the metrology modules. Exchange of the pairing key assures that communication originates or is received by the original modules that exchanged the pairing key. A pairing key could be a keyed-hash message authentication code, HMAC, key for integrity checks and/or a 256 AES key for encryption. A SHA256 keyed HMAC key would be an example of a key used for an integrity check. The pairing key assures confidentiality between the communication module and the metrology module. This is of importance since these modules are linked via an external link that can be tapped. In addition, since these modules may be separate, either on separate boards or in separate housings, any one of the modules may be replaced. Therefore, use of the pairing key to secure a paired channel on the external link between the communication module and any of the metrology modules assures that reliable communication is maintained during the operation of the meter.

Through the use of secure data exchanged between the head-end system and the meter, a secure channel may be established through the network between the head-end system and the endpoint, specifically between the head-end system and the communication module of the endpoint. This secure channel is extended within the meter by the exchange of identical or similar secure data between the communication module and the endpoint transmitted via the paired channel. The extension of the secure channel within the endpoint does not affect the flow of any communication between the head-end system and the endpoint. This aspect of the present invention helps detect tampering with the modules or the communication path at the meter.

The present invention will now be described with reference to the accompanying drawings, in which exemplary embodiments of the invention are shown. Examples are shown having a communication module connected to a metrology module. Note that this configuration may be extended to include a communication module connected to one or more metrology modules. This present invention is described by explaining the exchange of information between one communication module and one metrology module. This functionality can be duplicated to include exchange of information between the communication module and any one of the metrology modules.

FIG. 1 is a diagram illustrating a metering network. A metering network may include a head-end system 110 communicating over a network 120 to an endpoint 230. Head-end system 110 is the controller of the metering network. It provides command and control over the network, delivering the analytics-based information utilities need to manage the distribution of resources. The head-end system 110 may be a software platform that allows data reporting and system control. A head-end system may operate over any type of wired or wireless network including but not limited to, RF mesh, PLC (Power Line Carrier) and cellular networks. It enables a user to remotely program endpoints, schedule time-of-use periods and rates, handle remote disconnects, analyze critical peak usage, view load control indices, and perform other day-to-day functions. In addition, the head-end system 110 may manage the meter data collected from many endpoints, validating each data element.

Referring to FIG. 2, the network 120 that the head-end system may utilize to communicate to an endpoint may include devices such as collectors 215, routers 220, and other endpoints, 221-223. Communication may proceed utilizing any appropriate protocol and any appropriate network configuration. Protocols include, but are not limited to the 802.15.4, PRIME, G3, and TCP/IP protocols. Several endpoints may transmit data to a router 220. The router 220, in turn, may route data to a collector 215 in the network. A collector may receive data from multiple routers. The collector 215 communicates with the head-end system 110. The head-end system may receive and send information to multiple collectors.

The endpoints such as endpoint 230 may be meters that are usually in geographically dispersed locations such as homes or businesses. The meters are used to monitor a resource such as electricity, water, or natural gas. Meters measure the usage of the resource. Some meters may be smart meters that support a variety of service commands. These service commands may allow utilities to disconnect, or limit service remotely or manually at the meter. In addition, some meters may store an event log that contains entries of functions the meter has performed. Service commands may originate from the head-end system and are sent via the network to endpoints.

Referring to FIG. 3, an endpoint 230 may include two modules, a communication module 130 and a metrology module 140 that are externally linked via a communication path 150. These two modules may be housed in the same unit on separate boards hence the communication path 150 may be an on board socket. Alternatively, the modules may be housed separately and thus the communication path 150 may be a communication cable or other conductor. Since these two components may be physically separate, the communication module 130 and the metrology module 140 may be removed or replaced independent of each other. The function of the communication module 130 is to receive and send messages through the network 120. The function of the metrology module is to provide the functions necessary to manage the resource, in particular to measure the resource used. The communication module 130 may include a communication device 312 such as an antenna and a radio. Alternatively the communication device 312 may be any device that allows wireless or wired communication. The communication module may also include a processor 313, and memory 314. The communication device 312 is used to receive and send messages through the network 120. The processor 313 controls functions performed by the communication module 130 and the processor 313 utilizes memory 314 as needed. The second component of the endpoint 230 is the metrology module 140. The metrology module 140 may include a processor 321, memory 322, and measurement circuitry 323. The processor 321 in the metrology 140 controls functions performed by the metrology module 140 and utilizes the memory 322 as necessary. The measurement circuitry 323 handles the measuring of the resource and may also handle the recording of measurements taken. Both the communication module and the metrology module may include computer executable instructions stored in memory or in another type of computer-readable medium and one or more processors within the modules may execute the instructions to provide the functions described herein.

During manufacture or installation or initialization of a meter or endpoint 230, a pairing key 450 is exchanged between the communication module and the metrology module. If the pairing key is set during manufacture, it may be injected into the modules. Alternatively, if the pairing key is not set during manufacture, the exchange is performed through the transmission of the pairing key between these two modules via the communication path 150. Once the pairing key 450 is exchanged, a paired channel on the communication path is established between the communication module and the metrology module. In a configuration where there are multiple metrology modules, a pairing key is exchanged between the communication module and each of the metrology modules. This pairing key may be the same for each of the metrology modules or may be a different key for each of the modules. Hence, data that is exchanged utilizing the pairing key is transmitted via the pairing channel of the communication link. The pairing channel assures secure communication between a specific communication module and a specific metrology module, and thus prevents the unauthorized tampering or replacement of either the communication module or the metrology module. In addition, data that is not required to be secure may also be transmitted on the communication path. This data would be transmitted without a pairing key and hence would not use the pairing channel.

Communication through the network may be initiated by the head-end system 110. A communication from the head-end system is transmitted through the network 120 to a specified endpoint 230. The communication is routed through network 120 until it is received by the specified endpoint 230. Specifically, the request is received by the communication module 130 of endpoint 230. The communication module receives and handles the communication as appropriate. This may include validating that the communication is from a valid head-end system and acknowledging the request by responding to the request with an appropriate message that is sent to the head-end system.

In an embodiment of this invention, the communication transmitted may include a request to set up a secure channel between the head-end system 110 and the endpoint 230 using the network 120. This may be performed by the exchange of security data. In an embodiment of this invention, security data may be keying data which may include various cryptographic keys exchanged between the head-end system 110 and the communication module 130. As shown in FIG. 4, these keys may include an encryption/decryption key 410 to allow the encryption of messages, an integrity key such as authentication code 420, an endpoint message signing key 430 to assure messages were received by the endpoint, and an endpoint message verification key 440 to verify that messages originate from a valid endpoint. Once the exchange of security data is performed between the communication module 130 and the head-end system 110, a secure channel is set up through the network 120 between the head-end system 110 and the communication module 130. For example, a message from the head-end system 110 to the endpoint 230 to change the configuration of the device would be signed by the head-end system 110 using an endpoint message/signing key 430 and verified by the endpoint 230 using an endpoint message/verification key 440 before allowing the configuration to occur. The signing key could be an Elliptic Curve Digital Signature Algorithm (ECDSA) signature key sent from the head end system 110 and an ECDSA verification key used for verification on the endpoint 230.

To extend the secure channel to the metrology module within the endpoint, the communication module 130 and the metrology module 140 exchange the security data. For example, keying data such as the encryption/decryption key 410 that is sent by the head-end system 110 and is received by the communication module 130 is exchanged between the communication module 130 and the metrology module 140 via the paired channel. Likewise, an integrity key such as an authentication code 420 to assure that the data exchanged is unaltered, the endpoint message signing key 430 and the endpoint message verification key 440 that is exchanged between the head-end system 110 and the communication module 130 of the endpoint 230 is also exchanged between the communication module 130 and the metrology module 140 via the paired channel. Keying data can be used for confidentiality of data exchanged, such as a AES 256 key, and also for integrity or authentication of the data exchanged, such as a SHA256 keyed HMAC key. This aspect of the exchange of the same or similar security data within the endpoint 230 allows for secure communication within the endpoint 230 without requiring any changes to the head-end system 110.

To ensure the efficient transfer of messages between the communication module 130 and the metrology module 140, a security mechanism can be implemented where the same or similar security data exchanged between the head-end system 110 and the communication module 130 of the endpoint 230 may be exchanged between the communication module 130 and the metrology module 140. Similarly, in a configuration where there are multiple metrology modules connected to a communication module, the security mechanism would be implemented between the communication module and each of the metrology modules by the exchange of the same or similar security data exchanged between the head-end system and the communication module. This security mechanism, which comprises of a further exchange of security data, facilitates the exchange of information between the communication module 130 and the metrology module 140 because network data messages received from the head-end system 110 can pass through with minimal processing from the communication module 130 to the metrology module 140. Likewise, metrology data messages originating at the metrology module 140 can be sent by the communication module 130 over the secure channel of the network 120 with little or no processing by the communication module. Alternatively, the communication module may process messages from the head-end system to determine whether to send the messages to the metrology module. For example, the communication module can verify the signature on a message. If the signature verification fails when checked by the communication module, the communication module may not send the message to the metrology module and may either ignore the message or send a reply message indicating a failed signature comparison. In another example, the communication module can determine when a message received is relevant to the metrology module. By the exchange of keys, the communication module and the metrology module can implement the same security mechanism; therefore, this message can be directly passed to the metrology module without the communication module performing any key verification. The metrology module would perform the signature comparison and any other key verification needed. Also, note that the set-up and use of extending the secure channel within the endpoint 230 is transparent to the head-end system 110. That is, the head-end system 110 communicates to the endpoint 230 as originally set up. The head-end system may not know whether the communication module 130 and the metrology module 140 have exchanged security data. This is advantageous because no change is necessary to the head-end system 110 to incorporate secure communication within the endpoint 230.

Referring to FIG. 5, which shows how network data is received and processed by the communication module, the extension of secure communication within an endpoint 230 commences at 510 with a communication from the head-end system 110 to establish a secure channel on the network to an endpoint 230. This communication may contain security data such as keying data. Keying data comprises any information necessary for integrity checking or for the confidentiality of any information exchanged. Keying data may include but is not limited to encryption/decryption keys, integrity keys (i.e., authentication codes), endpoint message signing keys or endpoint message verification keys. At 520, the exchange of security data is performed between the communication module and the metrology module via the paired channel on the communication path. Once the secure channel is extended within the endpoint, the communication module may receive at 530 network data via the secure channel of the network. Network data may be any communication received by the communication module that is received via the secure channel on the network. The communication module determines the recipient of the network data at 540 and 550. In this example, the recipient may be either the communication module itself or the metrology module. In an alternative example where there are multiple metrology modules, the recipient may be either the communication module itself or any one of the metrology modules. If the network data is for the communication module then the communication module verifies keys such as signing keys or an authentication code and processes the network data at 560. Processing the network data may include decryption using a decryption key. If the network data is not for the communication module then the communication module determines if it is verifying keys at 580 before transmitting to the recipient. If the communication module verifies keys then it will do so on the network data and if keys are confirmed, the network data is sent to the metrology module at 570. Alternatively, if there are multiple metrology modules, the communication module may verify keys and proceed either by (1) determining from the network data the specific metrology module that is the intended recipient and transmit the network data to that recipient or (2) transmit the network data to all metrology modules. If the communication module does not verify keys then the network data is transmitted to the metrology module at 590. Alternatively, if there are multiple metrology modules and the communication module does not verify keys, the communication module may send the network data to each of the metrology modules and each metrology module would handle the network data accordingly. If a specific metrology module was not the intended recipient then that metrology module would discard the network data. If a specific metrology module was the intended recipient then that module would verify keys including but not limited to a signature key, any integrity key (authentication code), and will decrypt the message using a decryption key to process at 595.

Referring to FIG. 6, which shows how metrology data is sent over the secure channel, the extension of secure communication within an endpoint 230 commences at 610 with a communication from the head-end system 110 to establish a secure channel on the network to an endpoint 230. This communication may contain security data such as keying data. Keying data comprises any information necessary for integrity checking or for the confidentiality of any information exchanged. Keying data may include but is not limited to encryption/decryption keys, integrity keys (authentication codes), endpoint message signing keys or endpoint message verification keys. At 620, the exchange of security data is performed between the communication module and the metrology module via the paired channel on the communication path. Any one of the metrology modules may prepare the metrology data to send by encrypting the metrology data with the encryption key previously exchanged. Also, it may add any key necessary for integrity checking such as a verification key or authentication code. Once this is completed, the metrology module will transmit the metrology data to the communication module and the communication module will transmit the metrology data over the secure channel at 640. However, it is not necessary for the metrology module to prepare the metrology data prior to transmitting it to the communication module. The metrology module may transmit the metrology data to the communication module without any keying data other than the pairing key. In this example, the communication module would encrypt the data with the previously exchanged encryption key and add the keys necessary, such as but not limited to a verification key. Once this is completed, the metrology data is transmitted over the secure channel at 650.

In another example, network data received by the communication module may be distributed by default. In this example, any network data received by the communication module would be sent as is to all the metrology modules. Since the exchange of keying data would have established a paired channel, the metrology module would process all decryption and verification of keys necessary to process the network data. Likewise, to send metrology data, the metrology module would prepare metrology data with encryption and appropriate keys such as verification keys and transmit the metrology data to the communication module via the paired channel. The communication module would then transmit the metrology data as received via the secure channel.

The exchange of security data and establishing a pairing channel allows the processing of network data or metrology data to be processed in whole or in part by either the communication module or the metrology module. In other words, network data may be processed (decrypted and confirm keys) either completely by the communication module or completely by the metrology module. Also, the data may be processed in part by the communication module (i.e., decryption) and keys confirmed by the metrology module. Likewise, the transmittal of metrology data may be prepared (encryption and the insertion of keys) in whole or in part by the metrology module or the communication module. In addition, the processing of network data or metrology data in whole or in part by either the communication module or the metrology module does not affect any communication to or from the head-end system to the endpoint.

Note that any exchange of data between the communication module and the metrology module once the paired channel is established includes the pairing key. Hence any communication received by either module would be checked first to confirm the pairing key. If the pairing key does not match, the data sent may be discarded by the module receiving the data. In other words, if the pairing key does not verify, there is essentially no communication between the communication module and the metrology module.

General Considerations

While the present subject matter has been described in detail with respect to specific aspects thereof, it will be appreciated that those skilled in the art, upon attaining an understanding of the foregoing, may readily produce alterations to, variations of, and equivalents to such aspects. Accordingly, it should be understood that the present disclosure has been presented for purposes of example rather than limitation and does not preclude inclusion of such modifications, variations, and/or additions to the present subject matter as would be readily apparent to one of ordinary skill in the art. For example, although a metering implementation has been used for illustration, the invention may be extended to any type of network endpoint that includes a communication module and a second module, separate from the communication module. 

1. A network endpoint device, comprising: a communication module configured to communicate with a network and to communicate with a first module and a second module via a bidirectional communication path, wherein the first module, the second module, and the bidirectional communication path are within the network endpoint device; the first module; the second module; and the bidirectional communication path, wherein the bidirectional communication path includes a first secure paired channel between the communication module and the first module established by an exchange of a first pairing key between the communication module and the first module, and a second secure paired channel between the communication module and the second module established by an exchange of a second pairing key between the communication module and the second module, and wherein the communication module is operable to receive a communication from an external network device that includes security data and requests a secure channel to the network endpoint device, to send the security data to the first module using the first secure paired channel and the first pairing key, and to send the security data to the second module using the second secure paired channel and the second pairing key, wherein the first pairing key, the second pairing key, and the security data are distinct.
 2. The network endpoint device of claim 1, wherein the first module is operable to receive a second communication from the communication module and to decrypt network data associated with the second communication using the security data.
 3. The network endpoint device of claim 1, wherein the first module is operable to receive a second communication from the communication module and to verify at least one key associated with the second communication using the security data.
 4. The network endpoint device of claim 1, wherein the first module is operable to encrypt module data using the security data and send the encrypted data in a second communication to the communication module via the first paired channel using the first pairing key.
 5. The network endpoint device of claim 4, wherein the first module is further operable to include keying data in the second communication sent to the communication module.
 6. The network endpoint device of claim 1, wherein the communication module is operable to receive a second communication from the network, wherein the second communication includes network data, to select the first module as a recipient, and to send the second communication to the first module via the first paired channel using the first pairing key.
 7. The network endpoint device of claim 1, wherein the communication module is operable to receive a second communication, and to send the second communication to the first module and the second module by: sending the second communication to the first module using the first paired channel and the first pairing key; and sending the second communication to the second module using the second paired channel and the second pairing key.
 8. The network endpoint device of claim 1, wherein the first module is a metrology module.
 9. A method for securing communications within a network, wherein the network includes a plurality of endpoints and a first endpoint includes a communication module and at least one additional module, comprising: receiving, by the communication module, a network communication that includes security data to establish a secure channel between a central system and the first endpoint; sending, by the communication module, the security data to a first additional module via a secure paired channel using a first pairing key, wherein the secure paired channel was previously established by an exchange of the first pairing key between the communication module and the first additional module, and the first pairing key and the security data are distinct; receiving, by the communication module, a second network communication that includes network data; determining, by the communication module, that the first additional module is a recipient for the second network communication; sending, by the communication module, the second network communication to the first additional module via the secure paired channel using the first pairing key; and verifying, by the first additional module, a key associated with the second network communication using the security data.
 10. The method of claim 9, further comprising: decrypting, by the first additional module, the network data of the second network communication using the security data.
 11. The method of claim 9, further comprising: sending, by the communication module, the security data to a second additional module via a second secure paired channel using a second pairing key, wherein the second secure paired channel was previously established by an exchange of the second pairing key between the communication module and the second additional module.
 12. The method of claim 11, further comprising: receiving, by the communication module, a third network communication; determining, by the communication module, that the second additional module is a recipient for the third network communication; verifying, by the communication module, a key associated with the third network communication using the security data; sending, by the communication module, data from the third network communication to the second additional module via the second secure paired channel using the second pairing key.
 13. The method of claim 11, further comprising: decrypting, by the second additional module, the data of the third network communication using the security data.
 14. The method of claim 9, further comprising: replacing the first additional module with a replacement module; and establishing a secure channel between the communication module and the replacement module using the first pairing key or a replacement pairing key.
 15. A network endpoint device, comprising: a communication module, including a communication device for wirelessly communicating with a network device via a network; at least one additional module; and a bidirectional communication path connecting the communication module and the at least one additional module, wherein the bidirectional communication path includes a first paired channel established by an exchange of a first pairing key between the communication module and the at least one additional module, wherein the communication module is operable to receive a communication from the network device via the communication device that includes security data and that requests a secure channel to the network endpoint device, and to send the security data to the at least one additional module using the first paired channel and the first pairing key, wherein the security data and the first pairing key are distinct, and wherein the at least one additional module is operable to use the security data to decrypt data received from the network and encrypt module data sent to the network device.
 16. The network endpoint device of claim 15, further comprising: a second additional module, wherein the bidirectional communication path connects the communication module and the second additional module, and further includes a second paired channel established by an exchange of a second pairing key between the communication module and the second additional module.
 17. The network endpoint device of claim 15, wherein the at least one additional module is a metrology module and includes measurement circuitry.
 18. The network endpoint device of claim 15, wherein the at least one additional module is operable to receive a second communication from the communication module and to verify at least one key associate with the second communication using the security data.
 19. The network endpoint device of claim 16, wherein the communication module is operable to receive a second communication and to determine whether to send the second communication to the at least one additional module or to the second additional module.
 20. The network endpoint device of claim 16, wherein the communication module is operable to receive a second communication and to verify at least one key associated with the second communication. 